Solution route synthesis of dendrite Cu6Sn5 powders, anode material for lithium-ion batteries

Intermetallic dendrite particles, such as Cu₆Sn₅ compound, possible anode materials for high power lithium-ion batteries, can be synthesized by using solution technique. Solution route method can induce the formation of the compound by performing a redox reaction between metal chloride salts and metallic reducing powder in a suitable solvent. The morphological features and single-phase formation corresponding to different processing conditions including solvent type, reducing agent particle size, and reaction temperature, were determined. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) results illustrate the dendritic morphology of Cu₆Sn₅ particles with small amount of impurities, which can be synthesized by using ethylene glycol as solvent and zinc powder as reducing agent. Reducing agent particle size and reaction temperature have a very small effect on the formation of the Cu₆Sn₅ dendrite powder.     

闪蒸-气相色谱应用于鱼腥草挥发性组分研究

本文用一种新的分析方法闪蒸-气相色谱（FE—GC）来研究中药鱼腥草的挥发性组分，用质谱鉴定了其挥发性物质的化学组成，并和传统的水蒸气蒸馏法进行了对比。结果表明：该方法简单、快速、可靠，样品粉末可直接用于分析，不需要复杂费时的前处理过程，且样品需要量少。这对鱼腥草化学成分整体性研究和有效成分提取方法的开发具有非常重要的意义。     

层状Ni-Mn基锂离子电池正极材料进展

层状Ni—Mn基锂离子电池正极材料具有层状结构镍酸锂(LiNiO2)的高比容量以及尖晶石型结构锰酸锂(LiMn2O4)的高安全性、低价格等特点，是最有可能代替或部分代替LiCoO2的新型正极材料用于小型锂离子电池，同时也可望用作低成本、高安全性和大容量动力型锂离子电池的正极材料。本文综述了层状Li—Ni—Mn—O系化合物和LiNi1/3Mn1／3Co1/3O2的合成工艺、结构特点和电化学性能，阐述了层状Ni—Mn基锂离子电池正极材料的发展、研究开发现状和应用前景。     

Thermal and structural properties of spray pyrolysed CdS thin film

Using photo acoustic technique, the thermal properties of CdS thin films grown by spray pyrolysis are measured. Thermal diffusivity and conductivity in these films decrease at least two orders compared with bulk. These results are compared with our study on nano CdS and the other available literature. The comparison is good. The dependence of thermal diffusivity on the thickness of the layer or the size of the particles on the glass substrate are analysed from the present measurement and discussed. The dependence of thermal diffusivity on the thickness of the layer on the glass substrate is discussed.     

Crystal structure and spectroscopic studies of NaGd(PO3)4

Single crystals of gadolinium–sodium polyphosphate NaGd(PO₃)₄ were grown for the first time using a flux method and characterized by X-ray diffraction. This phosphate crystallizes in a monoclinic system with P2₁/n space group and with the following unit-cell dimensions: a = 9.767(3) Å, b = 13.017(1) Å, c = 7.160(2) Å, β = 90.564(5)°, V = 910.3(4) Å³ and Z = 4. The crystal structure was solved from 3451 X-ray independent reflections with final R(F²) = 0.0219 and R_w(F²) = 0.056 refined with 164 parameters (). The atomic arrangement can be described as a long chain polyphosphate organization. Two infinite (PO₃)∝ chains with a period of eight tetrahedra run along the [0 1 1] direction. The structure of NaGd(PO₃)₄ consists of GdO₈ polyhedra sharing oxygen atoms with phosphoric group PO₄. Each Na⁺ ion is bonded to eight oxygen atoms.     

Kinetics of reactive diffusion between Au and Sn during annealing at solid-state temperatures

The reactive diffusion between Au and Sn was experimentally studied at solid-state temperatures using Sn/Au/Sn diffusion couples prepared by a diffusion bonding technique. The diffusion couples were annealed at temperatures of T = 393 and 473 K for various times in an oil bath with silicone oil. After annealing, compound layers composed of AuSn₄, AuSn₂ and AuSn were recognized to form at the Au/Sn interface. The thickness of the AuSn₄ layer is about six and four times greater than those of the AuSn₂ and AuSn layers at T = 393 and 473 K, respectively. The ratio of the thicknesses of the compound layers is kept constant independently of the annealing time. The total thickness l of the compound layers is described as a function of the annealing time t by the equation l = k(t/t₀)ⁿ, where t₀ is unit time, 1 s. The exponent n is nearly equal to 1/2 at T = 393 K but takes a value between 1/4 and 1/2 at T = 473 K. Such an intermediate value of n at T = 473 K indicates that the grain boundary diffusion contributes to the reactive diffusion and the grain growth occurs at certain rates. As the annealing temperature decreases, the contribution of the grain boundary diffusion should become more remarkable, but the grain growth will slow down. Consequently, n becomes close to 1/2 at T = 393 K. According to the constancy of the ratio of the thicknesses, it is concluded that the same rate-controlling process works in the AuSn₄, AuSn₂ and AuSn layers at a constant annealing temperature.     

Blue-emitting cyanuric acid-melamine complexes from urea thermolysis

Novel blue-emitting cyanuric acid-melamine complexes CA_x·M_1−x (x = 0.8-0.9) have been prepared by a simple two-step procedure from urea. Relatively strong and pure blue-light emission with a maximum at 470 nm was observed from these complexes. These complexes are very promising light-emitting materials due to their good thermal stability.